Self-attaching nut

ABSTRACT

A self-attaching nut having a central pilot projecting from an end face of the body portion, an annular groove surrounding the pilot and an annular panel support face surrounding the groove, wherein the outer side wall includes a plurality of circumferentially spaced notches, each having an outer wall which extends from the bottom wall of the annular groove to the panel support face and the bottom wall of the groove includes a plurality of circumferentially spaced radial ribs integral with either the outer or inner side walls of the annular groove having a radial end spaced from the opposed side wall and a top face inclined toward the bottom wall of the annular groove providing improved torque resistance and push-off strength. Alternating circumferentially overlapping radial ribs integral with the pilot and the outer groove wall and ribs which extend below the bottom wall of the groove are also disclosed.

RELATED APPLICATIONS

This application is a continuation-in-part application of U.S. Ser. No.10/232,335 filed Aug. 30, 2002.

FIELD OF THE INVENTION

This invention relates to self-attaching female fasteners, particularlyincluding pierce and clinch nuts, which may be formed by conventionalcold header techniques including secondary operations and which provideimproved retention and resistance to rotation of the fastener on a panelfollowing installation.

BACKGROUND OF THE INVENTION

Self-attaching female fasteners, including pierce and clinch nuts,formed by cold header techniques and secondary press operationsgenerally include a body portion having an end face, a central pilotportion projecting from the end face of the body portion having a borethrough the central pilot portion, an annular groove in the end face ofthe body portion surrounding the pilot portion and an annular panelsupport face or flange portion surrounding the annular groove.Generally, at least one of the inner and outer side walls of the annulargroove are inclined toward the other side wall to provide a restrictedopening to the annular groove adjacent the annular panel support face toimprove retention of the fastener following installation. Furtherimproved retention of the fastener on a panel is provided by incliningboth the inner and outer side walls of the annular groove toward theopposing side wall forming a “dovetail” shaped re-entrant groove. Whenthe panel is deformed against the bottom wall of the groove by a diemember or die button having a projecting annular lip configured to bereceived in the annular groove, the panel is simultaneously deformedbeneath the undercuts provided by the dovetail shaped re-entrant groove.Alternatively, the outer side wall of the annular groove may be inclinedtoward the pilot portion and the pilot portion may be deformed radiallyoutwardly during installation as disclosed, for example, in U.S. Pat.No. 6,276,040 to form a secure installation having sufficient push-offstrength. However, most installations of self-attaching nuts alsorequire sufficient torque resistance or anti-rotation means preventingrotation of the self-attaching fastener on the panel followinginstallation, particularly where the nut and panel assembly is attachedto a second component by a bolt or other male threaded member using atorque wrench or the like.

The prior art discloses various anti-rotation or torque resistant meansfor self-attaching female fasteners of this type. For example, U.S. Pat.No. 5,531,552, assigned to the predecessor in interest of thisapplication, discloses forming a plurality of circumferentially spacedprotrusions having radial channels therebetween in the bottom wall ofthe groove which provides improved torque resistance. U.S. Pat. No.5,549,430, also assigned to the predecessor in interest of the assigneeof this application, discloses a self-attaching nut of this type,wherein the bottom wall of the groove includes a plurality of spacedarcuate or semi-circular protrusions integral with the pilot portionwhich provide improved torque resistance, but which also deforms panelmetal beneath the inclined outer side wall of the annular groove, alsoproviding improved push-off strength following installation. U.S. Pat.No. 5,782,594 discloses a pierce nut having a central recess, ratherthan a groove having an inner side wall and a plurality ofcircumferentially spaced radial notches or pockets formed in the panelsupport face which, when formed by a die member, forms radially inwardlyprojecting bead-like projections in the side wall of the recess,providing improved torque resistance. The above-referenced U.S. Pat. No.6,276,040, also discloses opposed V-shaped webs integral with the bottomwall of a dovetail shaped annular groove and the opposed inner and outerside walls of the annular groove. Further, the prior art includes piercenuts of this type having rectangular radial ribs or lugs which bridgethe bottom wall of the annular groove and are integral with both theinner and outer side walls of the groove. However, where the ribs areintegral with both the inner and outer side walls of the annular groove,deformation of a panel against the ribs may cause deformation ordistortion of the thread cylinder unless the pilot is reinforced.

However, many applications of self-attaching nuts of this type formed bycold heading require further improved integrity of the nut and panelassembly, including improved torsion resistance and push-off strength.The embodiments of the improved self-attaching nut of this inventionprovides improved integrity of the nut and panel assembly, includingimproved torsion resistance and push-off strength.

SUMMARY OF THE INVENTION

The self-attaching nut or female fastener element of this invention maybe formed by conventional cold header techniques and may be utilized asa pierce or clinch nut to provide superior integrity in a fastener andpanel assembly, including improved torsion resistance and push-offstrength. As used herein, the term “self-attaching nut,” includes bothpierce and clinch nuts. During installation of a pierce nut, the centralpilot portion pierces or punches an opening in the panel and the panelis then deformed into the annular groove by a die member or die button.A clinch nut is installed in a preformed panel opening, but a pierce nutmay also be utilized as a clinch nut. The self-attaching nut of thisinvention includes a body portion having an end face, a central pilotportion projecting from the end face having a bore therethrough, anannular groove in the end face surrounding the pilot and an annularpanel support face or flange portion surrounding the annular groove. Theannular groove includes an inner side wall adjacent the pilot portion, abottom wall and an outer side wall extending from the bottom wall to thepanel support face. In the preferred embodiments of the self-attachingnut of this invention, at least one of the inner and outer side walls ofthe annular groove is inclined toward the other side wall forming arestricted opening to the annular groove. In a preferred embodiment ofthe self-attaching nut of this invention, the outer side wall of theannular groove is inclined toward the pilot portion and in the mostpreferred embodiment, both side walls of the groove are inclined to theother side wall, forming a dovetail-shaped re-entrant groove, whereinthe outer side wall is inclined toward the pilot portion and the innerside wall is inclined toward the outer side wall providing improvedpush-off strength. However, as set forth above, the prior art includesself-attaching nuts having the features thus far described.

As set forth below, this application discloses several embodiments ofthe self-attaching nut of this invention having improved torqueresistance. The improvements described below may be utilized in variouscombinations to provide improved torque resistance and push-off strengthdepending upon the application.

One feature of the self-attaching nut of this invention is that theouter side wall of the annular groove includes a plurality ofcircumferentially spaced radial notches each having an outer side walland opposed generally radial walls. In a preferred embodiment, thenotches extend from the bottom wall of the annular groove to the annularpanel support face. During installation of the self-attaching nut to apanel, the panel is deformed radially into the radial notches providingimproved torque resistance. In a preferred embodiment, wherein the outerside wall of the annular groove is inclined radially inwardly toward thepilot portion, the outer wall of the notches may extend generally orsubstantially perpendicular to the annular support face of theself-attaching nut.

Further improvement in torque resistance may be provided by radial ribsprojecting from the bottom wall of the annular groove each having a topface spaced from the bottom wall. In one preferred embodiment, theradial ribs are integral with the outer side wall of the annular grooveat or above a midportion of the outer side wall and the top face of theribs is inclined from the outer side wall toward the bottom wall of theannular groove but spaced from the inclined inner side wall of theannular groove, thereby providing improved torque resistance, but alsodeforming the panel beneath the inclined inner side wall and providingimproved push-off strength. In one preferred embodiment, the radialinner ends of the radial ribs merge with the bottom wall flush with thebottom wall. In another preferred embodiment, the radial ribs continue“beneath” the bottom wall of the bottom wall in radial channels, suchthat the top face of the radial ribs extends below the plane of thebottom wall providing further improved torque resistance.

In the disclosed embodiments, the radial ribs may be generallyrectangular in cross-section having a planar top face, but preferablyinclude outwardly inclined side faces which direct panel metal into thebottom wall of the groove. In one preferred embodiment, the radial ribsare integral with the inwardly inclined outer side wall of the annulargroove and spaced between the radial notches. In another preferredembodiment, the radial ribs are integral with the outer wall of theradial notches, but preferably have a width measured circumferentiallyless than the circumferential width of the radial notches, such thatpanel metal will flow around the radial ribs into the radial notches. Asused herein, the phrase “integral with the outer side wall” of theannular groove includes radial ribs integral with either the inclinedouter side wall of the annular groove, when used, or the outer wall ofthe radial notches, because the outer wall of the radial notches, whenused, further define the outer side wall of the annular groove. Inanother preferred embodiment, the radial ribs are integral with theinner side wall of the annular groove, are inclined toward the bottomwall and spaced from the outer wall as described above with regard tothe preferred embodiments wherein the radial ribs are integral with theouter side wall. In this embodiment, the top face of the radial ribs mayextend radially beneath the plane of the bottom wall of the annulargroove in a radial channel, as described above.

Further improvement in torque resistance may be provided by cooperationof the radial ribs. In one preferred embodiment, a pair of radial ribsis provided in a plurality of the radial notches integral with the outerwall of the radial notches, wherein the opposed radial ribs each includea top face which may extend to the panel support face surrounding theannular groove, opposed outwardly inclined faces, which are angledtoward the opposed face of the adjacent radial rib, directing panelmetal between the ribs and preferably including inwardly inclined facesforming an undercut between the pair of ribs providing further improvedpush-off strength and torque resistance. In another embodiment, thecircumferentially spaced radial ribs comprise alternating radial ribsintegral with the inner side wall or pilot portion and the outer sidewall, wherein the radial ribs have a radial length greater than one-halfthe radial width of the bottom wall of the annular groove, such that theribs overlap circumferentially providing further improved torqueresistance. In this embodiment, the radial ribs are inclined toward thebottom wall, but spaced from the opposed wall, such that, duringinstallation, panel metal is deformed radially outwardly by the ribsintegral with the inner wall of the annular groove beneath the inclinedouter wall and radially inwardly beneath the inclined inner side wall bythe radial ribs integral with the outer side wall.

Further improved push-off strength is provided by radial ribs integralwith either the inner or outer side wall of the annular groove having anend portion spaced from the other side wall above the plane of thebottom wall and an inwardly inclined end face integral with the bottomwall forming an undercut and entrapping panel metal during installation.As will be understood from the above description, in the preferredembodiments of the self-attaching nut of this invention, the radial ribsare integral with one of the inner and outer side walls of the annulargroove each having an end portion spaced from the opposed side wall andthe radial ribs preferably include a top face which is angled toward thebottom wall. However, a similar effect may be provided by a radial ribintegral with either the inner or outer side wall, angled toward thebottom wall, wherein the radial end portion is adjacent the opposedinner or outer side wall and including a circumferential channel.

As will be understood from the above summary of the invention, severalembodiments of the self-attaching nut of this invention are disclosedherein which include improved integrity when installed in a panel,including push-off strength and torque resistance. Further advantagesand meritorious features of the self-attaching nut of this inventionwill be more fully understood from the following description of thepreferred embodiments, the appended claims and the drawings, a briefdescription of which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top perspective view of one embodiment of the self-attachingnut of this invention;

FIG. 2 is a top view of the self-attaching nut shown in FIG. 1;

FIG. 3 is a side cross-sectional view of FIG. 2 in the direction of viewarrows 3-3;

FIG. 3A is an enlarged cross-sectional view of the annular groove in theembodiment of the self-attaching nut shown in FIGS. 1 to 3;

FIG. 4 is an enlarged cross-sectional view of FIG. 3 in the area of viewcircle 4;

FIG. 5 is a partial cross-sectional view of FIG. 4 in the direction ofview arrows 5-5;

FIG. 6 is a top perspective view of an alternative embodiment of theself-attaching nut of this invention;

FIG. 7 is a top view of the self-attaching nut shown in FIG. 6;

FIG. 8 is a partial side cross-sectional view of FIG. 7 in the directionof view arrows 8-8;

FIG. 9 is a partial cross-sectional view of FIG. 8 in the direction ofview arrows 9-9;

FIG. 10 is a partial cross-sectional view of FIG. 8 in the direction ofview arrows 10-10;

FIG. 11 is a top perspective view of a further alternative embodiment ofthe self-attaching nut of this invention;

FIG. 12 is a top view of the self-attaching nut shown in FIG. 11;

FIG. 13 is a partial side cross-sectional view of FIG. 12 in thedirection of view arrows 13-13;

FIG. 14 is a partial cross-sectional view of FIG. 13 in the direction ofview arrows 14-14;

FIG. 15 is a partial cross-sectional view of FIG. 13 in the direction ofview arrows 15-15;

FIG. 16 is a top perspective view of a further alternative embodiment ofthe self-attaching nut of this invention;

FIG. 17 is a partial side cross-sectional view of FIG. 16 in thedirection of view arrows 17-17;

FIG. 18 is a top perspective view of a further alternative embodiment ofthis invention;

FIG. 19 is a partial top view of the embodiment of the self-attachingnut shown in FIG. 18;

FIG. 20 is a partial cross-sectional view of FIG. 19 in the direction ofview arrows 20-20;

FIG. 21 is a top perspective view of a further alternative embodiment ofthe self-attaching nut of this invention;

FIG. 22 is a partial top view of the self-attaching nut shown in FIG.21;

FIG. 23 is a partial cross-sectional view of FIG. 22 in the direction ofview arrows 23-23;

FIG. 24 is a partial cross-sectional view of FIG. 23 in the direction ofview arrows 24-24;

FIG. 25 is a top perspective view of a further alternative embodiment ofthe self-attaching nut of this invention;

FIG. 26 is a partial top view of the self-attaching nut shown in FIG.25; and

FIG. 27 is a partial cross-sectional view of FIG. 26 in the direction ofview arrows 27-27.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As will be understood, the following description of the preferredembodiments and the appended drawings are for illustration purposes onlyand do not limit the scope of this invention except as set forth in thefollowing claims. FIGS. 1 to 5 illustrate a first embodiment of theself-attaching nut 20 of this invention including a body portion 22having an-end face 24 (see FIG. 1), a central pilot portion 26, anannular groove 28 surrounding the pilot portion 26 and an annular panelsupport face 30 surrounding the annular groove 28. The pilot portion 26includes an annular preferably planar end face 32 and a bore 34 throughthe pilot portion. Where the self-attaching nut 20 of this invention isutilized as a pierce nut, the end face 32 is preferably above the planeof the annular panel support face 30, as best shown in FIG. 3, such thatthe pilot portion 26 pierces an opening in a metal panel as is wellknown in this art. As best shown in FIG. 3A, the annular groove 28includes an inner side wall 36 which, in the disclosed embodiment, isalso the outer side wall of the pilot portion 26, a bottom wall 38 andan outer side wall 40. As set forth above, in the preferred embodimentsof the self-attaching nuts of this invention, at least one of the innerand outer side walls 36 and 40, respectively, is inclined toward theopposed side wall forming a restricted opening to the annular groove 28.In a preferred embodiment of this invention, the outer side wall 40 isinclined toward the pilot portion 26 or more specifically toward theinner side wall 36 and in the most preferred embodiment, the inner andouter side walls 36 and 40 are inclined toward each other as shown inFIG. 3A, forming a dovetail-shaped re-entrant groove providing improvedpush-off strength when the self-attaching nut is installed in a panel(not shown). The bore 34 may be threaded as shown or the bore 34 may becylindrical for receipt of a thread forming or thread rolling malefastener, such as a screw or bolt. The body portion 22 may be polygonalas shown having a plurality of flat faces 42 or the outer surface of theself-attaching nut may also be cylindrical. As thus far described, theself-attaching nut of this invention is generally conventional, althoughseveral of the prior art references do not include both an inner andouter inclined side wall 36 and 40, respectively, which results inreduced push-off strength.

As set forth above, the self-attaching nut of this invention providesimproved integrity of the nut and panel assembly, including improvedtorque resistance and push-off strength. One important feature of theself-attaching nut shown in FIGS. 1 to 5 is the circumferentially spacedradial notches 44 each having an outer wall 46 and opposed generallyradial walls 48. The radial walls 48 may also be inclined inwardlytoward each other from the outer wall 46 (not shown) to provide furthertorque resistance. As best shown in FIG. 3, the outer wall 48 of theradial notches extends generally perpendicular to the panel planarsupport face 30 in the disclosed embodiment. Further, in a preferredembodiment, the radial notches 44 extend from the bottom wall 38 of theannular groove 28 to the top annular panel support face 30. As will beunderstood, during installation of the self-attaching nut 20, a panel(not shown) will be deformed into the radial notches 44 providingsubstantially improved torque resistance. In the disclosed embodiment,the self-attaching nut 20 includes eight radial notches 44 and the bodyportion includes eight flats 42, wherein the radial notches 44 aredefined in the corner portions 50 (see FIG. 1), providing maximum torqueresistance.

Although the radial notches 44 may be used alone to provide torqueresistance, the embodiment of the self-attaching nut 20 illustrated inFIGS. 1 to 5 further includes a plurality of radial ribs 52. In thisembodiment of the self-attaching nut 20 of this invention, the radialribs 52 are integral with the inclined outer side wall 40 of the annulargroove 28. Each of the radial ribs 52 include a top face 54 which isinclined from the outer side wall 40 of the annular groove 28 toward thebottom wall 38. In the disclosed embodiment of the self-attaching nut20, the radial inner ends 56 of the radial ribs 52 merge with the bottomwall 38 as best shown in FIG. 4 and the radial inner ends 56 of the ribs52 are spaced from the inner side wall 36 of the annular groove 28 asbest shown in FIGS. 1 and 2. In the disclosed embodiment, the top face54 of the radial ribs 52 is generally rectangular; however, the sidefaces 58 of the radial ribs are preferably angled outwardly as bestshown in FIG. 5. The outwardly inclined faces 58 direct panel metaltoward the bottom wall 38 of the annular groove 28, improving filling ofthe annular groove 28 with panel metal during installation. Further, theinclined top faces 54 of the radial ribs 52 direct panel metal radiallyinwardly beneath the inclined inner side wall 36 as the panel metal isdeformed against the radial ribs 52, providing further improved torsionresistance and push-off strength.

As will be understood by those skilled in this art and described furtherin the above-referenced U.S. patents, the self-attaching nut 20illustrated in FIGS. 1 to 5 may be utilized as a pierce nut, wherein theplanar annular end face 32 of the central pilot portion 26 is drivenagainst a panel (not shown) which is supported on a die button (notshown) and the pilot portion then pierces an opening in the panel whichreceives the pilot portion 26 therethrough. The die button will includean annular lip configured to be received within the annular groove 28which deforms the panel surrounding the panel opening into the annulargroove 28 and against the bottom wall 38 and the top faces 54 of theradial ribs 52. The inclined top face 54 of the radial ribs then directspanel metal beneath the inclined inner side wall 36, providing improvedretention and the panel metal is further deformed around the inclinedside faces 58 of the radial ribs and into the radial notches 44providing further improved torque resistance. In a preferred embodiment,the inclined top face 54 is spaced below the annular panel support face30 and integral with the inclined outer side wall 40 at or above themidportion 60 (i.e., about one half the distance between the bottom wall38 and the panel support face 30) of the inclined outer side wall 40 asshown in FIG. 4, providing optimum torque resistance. As will now beunderstood, the radial notches 44 in combination with the radial ribs 52provide superior torque resistance and further improve the push-offstrength or integrity of the nut and panel installation.

FIGS. 6 to 10 illustrate a second embodiment of a self-attaching nut 120of this invention, wherein the common elements of the self-attaching nut120 are numbered the same as the elements of the self-attaching nut 20described above except that the elements of the self-attaching nut 120are numbered in the 100 series to simplify the description of theself-attaching nut 120. That is, the self-attaching nut 120 shown inFIGS. 5 to 10 include a body portion 122 having an end face 124, acentral pilot portion 126, an annular groove 128 surrounding the pilotportion and an annular panel support face 130 surrounding the annulargroove 128. In this embodiment of the self-attaching nut 120, the radialribs 152 are integral with the inclined outer side wall 140, generallyequally spaced between the radial notches 144, as described above inregard to the self-attaching nut 20 shown in FIGS. 1 to 5. However, thetop face 154 of the radial ribs extends below the plane of the bottomwall 138 of the annular groove 128, as best shown in FIG. 8, wherein theradial inner end portion 156 of each of the radial ribs 152 is receivedin a radial channel 162 as shown in FIGS. 8 and 10. The radial inner end156 of the radial ribs 152 is, however, spaced from the inner side wall136 of the annular groove in that it is not integral with the outer wallof the pilot portion or the inclined inner wall 136 of the annulargroove. All other features of the self-attaching nut 120 may beidentical to the self-attaching nut 20 described above with regard toFIGS. 1 to 5.

The second embodiment of the self-attaching nut 120 shown in FIGS. 6 to10 has further advantages over the self-attaching nut 20 shown in FIGS.1 to 5. First, during installation of the self-attaching nut 120 in apanel (not shown), the panel metal will be driven against the inclinedtop face 154 into the radial channels 162 in the bottom wall 138 of theannular groove 128, providing further improved torque resistance.Further, the panel will be driven beneath the inclined inner side wall136 by the inclined radial top face 154 which extends to adjacent theinclined inner side wall 136, providing further improved push-offstrength. The remaining features of the second embodiment of theself-attaching nut shown in FIGS. 6 to 10 may be identical to theself-attaching nut 20 described in more detail above, and therefore nofurther description of the second embodiment is necessary for a fullunderstanding of this embodiment.

The third embodiment of the self-attaching nut 220 shown in FIGS. 11 to15 is essentially identical to the second embodiment shown in FIGS. 6 to10, except that the radial ribs 252 are integral with the inner sidewall 236 of the annular groove 228 which, in the disclosed embodiment,is also the external surface of the central pilot portion 226. That is,the self-attaching nut 220 includes a central pilot portion 226, anannular groove 228 surrounding the pilot portion and an annular panelsupport face 230 surrounding the annular groove 228. Except as describedabove, the self-attaching nut 220 is identical to the self-attaching nut120 described above and the elements of the self-attaching nut 220 arenumbered the same as the elements of the self-attaching nut 120 exceptthat the reference numbers of this third embodiment are numbered in the200 series.

In this third embodiment of the self-attaching nut 220, panel metal isdriven against the bottom wall 238 of the annular groove 228 and theoutwardly inclined top faces 254 of the radial ribs 252 duringinstallation of the self-attaching nut in a panel (not shown). The panelmetal is thus driven beneath the inclined outer side wall 240 and intothe radial channels 262 by the inclined top faces 254, providing a verysecure installation with improved torque resistance as described abovewith regard to the self-attaching nut 120. Further, as described abovewith regard to the self-attaching nut 20, the panel metal issimultaneously driven into the radial notches 244 in the outer side wall240. Further, in this third embodiment, there is less likelihood ofdistortion of the threaded bore 234 because the radial ribs 252 do notdrive panel metal toward the pilot portion 226. As set forth above, allother elements or features of the self-attaching nut 220 may beidentical to the self-attaching nuts 20 and 120 described above andtherefore, no further description of this embodiment is required for afull understanding of this embodiment.

The fourth embodiment of the self-attaching nut 320 shown in FIGS. 16and 17 differs from the embodiment of the self-attaching nut 20 shown inFIGS. 1 to 5 in two material respects. First, the bottom wall 338 of theannular groove 328 includes a plurality of alternating circumferentiallyspaced ribs 352 and 353, including a first plurality ofcircumferentially spaced radial ribs 352 integral with the outer sidewall of the annular groove 328 and a second plurality of radial ribs 353integral with the inner side wall 336 of the annular groove 328. In apreferred embodiment of the self-attaching nut 320, the radial ends 356of the radial ribs 352 and 353 extend beyond a midportion 364 of theannular groove 328, such that the alternating radial ribs 352 and 353circumferentially “overlap.” That is, the radial inner ends 356 of theradial ribs 352 extend beyond the radial inner ends 356 of the radialribs 353 in the bottom wall 338 of the annular groove 328, such that theradial ribs 352 and 353 circumferentially overlap, as best shown in FIG.16. This alternately overlapping radial ribs 352 and 353 providesuperior torque resistance. Further, upon installation of theself-attaching nut 320 in a panel, the top faces 354 of the radial ribs352 and 353 direct panel metal beneath both the inclined inner side wall336 and the inclined outer side wall 340 providing improved push-offstrength.

The second difference of the self-attaching nut 320 shown in FIGS. 16and 17 is that the radial ribs 352 are integral with the outer wall 346of the radial notches 344, but have a circumferential width less thanthe circumferential width of the radial notches measured between theopposed radial walls 348. As described above with regard to theembodiment of the self-attaching nut 20 shown in FIGS. 1 to 5, the sidefaces 358 of the radial ribs 352 and 353 are inclined outwardly from thetop face 354 which, during installation of the self-attaching nut 320 ina panel (not shown), directs panel metal between the radial ribs 352 andthe opposed radial walls 348. In a preferred embodiment of theself-attaching nut 320, the radial outer end of the radial notches 352is spaced below the plane of the annular panel support face 330 at orabove a midportion of the outer walls 346, such that the panel metalwill fill the upper portion of the radial notches 344.

The self-attaching nut 320 shown in FIGS. 16 and 17 provide furtheradvantages over the self-attaching nuts previously described. First, thealternating overlapping radial ribs 352 and 353 provide superior torqueresistance over the previously described embodiments. Second, becausethe inclined top faces 358 of the radial ribs 352 and 353 alternateradially inwardly and outwardly toward the inner and outer side walls336 and 340, respectively, more panel metal is driven beneath theinclined inner and outer side walls 336 and 340, providing improvedpush-off strength and balancing the forces resulting from the panelbeing driven against the radial ribs. Finally, forming the radial ribs352 integral with the outer wall 346 of the radial notches 344 locatesthe radial ribs further from the axis of the bore 334, providing furthertorque resistance.

As set forth above, the self-attaching nut 320 shown in FIGS. 16 and 17may otherwise be identical to the self-attaching nut 20 described abovewith regard to FIGS. 1 to 5 and have been numbered the same, except thatthe elements are numbered in the 300 series and therefore no furtherdescription is required for a complete understanding of this embodimentof the self-attaching nut of this invention.

The fifth embodiment of the self-attaching nut 420 of this inventionshown in FIGS. 18 to 20 differs from the embodiment of theself-attaching nut 20 shown in FIGS. 1 to 5 in two material respects. Asset forth above in the Background of the Invention, it is not desirableto utilize radial ribs which bridge the inner and outer side walls ofthe annular groove to avoid thread distortion. In the second preferredembodiments of the self-attaching nuts of this invention, the radialribs are integral with either the inner or outer side walls of theannular groove, but spaced from the opposed wall, particularly where theradial ribs are integral with the outer side wall as described abovewith regard to the embodiments of the self-attaching nuts 20, 120, 220and 320 described above. In the embodiment of the self-attaching nut 120shown in FIGS. 6 to 10, the radial ribs 152 extend below the plane ofthe bottom wall 138 and are therefore not integral with the outer sidewall of the pilot portion 126, further reducing the likelihood of threaddistortion. In this fifth embodiment of the self-attaching nut 420, theradial ribs 452 extend to adjacent the inner side wall 436 of theannular groove 428 above the plane of the bottom wall 438 as best shownin FIG. 20. However, the radial ribs 452 further include circumferentialchannels 464 having opposed faces 466 which, in the disclosedembodiment, extend to the bottom wall 438 of the annular groove 428 asbest shown in FIG. 20. Thus, the inwardly directed force duringinstallation of this embodiment of the self-attaching nut 420 in a panel(not shown), the inward force of a panel against the top faces 254 isreduced, reducing the likelihood of distortion of the threads of thebore 434. It is also believed that this embodiment of the self-attachingnut 420 may provide further torque resistance because of the increasedarea of the side faces 458 of the radial ribs 452. The remainingfeatures or elements of the self-attaching nut 420 shown in FIGS. 18 to20 may be identical to the embodiment of the self-attaching nut 20 shownin FIGS. 1 to 5 and have therefore been numbered the same as theself-attaching nut 20 except that the self-attaching nut 420 is numberedin the 400 series. Therefore, no further description of the embodimentof the self-attaching nut 420 is necessary for a complete understandingof this embodiment.

The sixth embodiment of the self-attaching nut 520 shown in FIGS. 21 to24 differs from the embodiments of the self-attaching nuts previouslydescribed in that a plurality of the circumferentially spaced radialnotches 544 include a pair of circumferentially spaced radial ribs 552and 553 integral with the outer wall 546 and one of the opposed radialwalls 548 of the radial notches 544, as shown. In this embodiment, theradial ribs 552 and 553 each include a top face 554 which may extend tothe panel support face 530 as shown in FIGS. 23 and 24 or spaced belowthe panel support face 530 as described above with the previousembodiments. The radial ribs 552 and 553 further include opposedoutwardly inclined faces 568 and opposed inwardly inclined faces 570,wherein the inwardly inclined faces 570 form an undercut as shown inFIG. 24. Thus, during installation of the self-attaching nut 520 in apanel (not shown), the panel metal is deformed against the opposedoutwardly inclined faces 568 and beneath the opposed inwardly inclinedfaces 570 against the bottom wall 538 of the annular groove. Further,the radial inner ends 556 of the radial ribs 552 and 554 are spacedabove the plane of the bottom wall 538 of the annular groove 528 andinclude an inwardly inclined end face 572 as shown in FIG. 23. As shownin FIGS. 21 and 22, the radial ribs 552 and 553 are located inalternative radial notches 544. That is, four of the radial notches 544include a pair of radial ribs 552 and 553 and the remaining four radialnotches are clear or open as described above with regard to FIG. 1.

The sixth embodiment of the self-attaching nut 520 shown in FIGS. 21 to24 and described above provides further advantages over the embodimentspreviously described. As will be understood by those skilled in thisart, a die member (not shown) utilized to install the self-attaching nut520 will include an annular lip portion as utilized for installingself-attaching nuts of this type and shown in the above-referencedpatents. However, the annular lip may further include radial portionsfor receipt between each pair of radial ribs 552 and 553. Thus, duringinstallation, panel metal is deformed between the radial ribs 552 and553 against the opposed outwardly inclined faces 568 and beneath theopposed inwardly inclined faces 570, providing further improved torqueretention and push-off strength. Further, as the panel metal is deformedagainst the bottom wall 538 of the annular groove 528, panel metal willbe deformed beneath the inwardly inclined end faces 572 of the radialribs 552 and 553, providing further improved push-off strength. Finally,the increased area, of the side faces 558 and the location of the radialribs integral with the outer wall 546, provides further improved torqueresistance. This increased torque resistance reduces the required numberof radial ribs. All other elements or features of the self-attaching nut520 may be identical to the self-attaching nuts previously described andthe reference numbers are identical to the previously describedself-attaching nuts, except that the reference numbers are in the 500series. That is, the self-attaching nut 520 includes a central pilotportion 526 having a bore 534 therethrough, an annular groove 528surrounding the pilot portion 526 and an annular panel support face 530surrounding the annular groove 528.

Finally, the seventh embodiment of the self-attaching nut 620 shown inFIGS. 25 to 27 differs from the embodiment of the self-attaching nut 520shown in FIGS. 21 to 24 in that each of the radial notches 644 includesonly one radial rib 652 integral with the outer wall 646 of the radialnotches 644, generally equally spaced between the radial walls 648. Thatis, in the embodiment of the self-attaching nut 620 shown in FIGS. 25 to27, each of the radial notches 644 includes a radial rib 652 integralwith the outer wall 646 of the radial notches having a circumferentialwidth less than the circumferential width of the radial notches 644measured between the opposed radial walls 648, wherein the radial ribs652 extend to the panel support face 630 as shown in FIG. 27 and theradial inner ends 656 of the radial ribs 652 is spaced above the planeof the bottom wall 638 of the annular groove 628 and the radial ribs 652each include inwardly inclined end faces 672 as shown in FIG. 27. Aswill be understood, however, the radial ribs 652 may also have a widthequal to the width of the notches 644. Except as described above, theself-attaching nut 620 may be identical to the embodiment of theself-attaching nut 520 and the previously described embodiments andtherefore the self-attaching nut 620 is numbered the same, except thatthe reference numbers are in the 600 series.

During installation of the seventh embodiment of the self-attaching nut620 shown in FIGS. 25 to 27 in a panel (not shown), panel metal isdeformed against the bottom wall 638 and the inwardly inclined top faces654 of the radial ribs 652. The top faces 654 of the radial ribs 652then deform the panel metal radially inwardly beneath the inclined innerside wall 636 and beneath the inwardly inclined end faces 672 providingimproved push-off strength. The panel metal is further deformedcircumferentially against the inclined side faces 658 into the radialnotches 644 and against the side faces 658 to the bottom wall 638 of theannular groove 628. Because the side faces 658 of the radial ribs 652have a greater surface area, the radial ribs 652 provide greater torqueresistance than where the radial ribs extend to a midportion of theouter wall.

As will now be understood from the above description of the embodimentsof the self-attaching nut of this invention, the improvements in torqueresistance and push-off strength provided by the various embodiments ofthe self-attaching nuts disclosed herein may be utilized individually orin combination to provide improved torque resistance and push-offstrength. In the preferred embodiments, the radial ribs are integralwith either the inner or outer side walls of the annular groove and theradial inner ends of the radial ribs are preferably spaced from theopposed side wall. In the more preferred embodiments, the radial ribsare integral with the outer wall of the annular groove, but may beintegral with either the inclined outer side wall of the annular grooveor the outer wall of the radial notches which, in a preferredembodiment, extends generally perpendicular to the panel support facesurrounding the annular pilot. However, as set forth above, the outerwall of the radial notches, when utilized, forms the outer side wall ofthe annular groove and thus, as used herein, reference to the radialnotches as integral with the outer side wall includes radial notchesintegral with the outer wall of the radial notches. In a preferredembodiment, the outer side wall of the annular groove is inclined towardthe pilot portion and the inner side wall of the annular groove isinclined toward the outer side wall, forming a dovetail-shaped annulargroove providing improved push-off strength. In the disclosedembodiments of the self-attaching nuts, the bottom wall of the annulargroove extends generally perpendicular to the axis of the bore throughthe pilot portion. However, the bottom wall may also be inclined towardeither the inner or outer side wall of the annular groove. Further, aswill be understood by those skilled in this art, the bottom wall must beinclined toward either the inner or outer side wall of the annulargroove a few degrees to permit removal of the self-attaching nut from adie member used to form the annular groove. This would be true of anyself-attaching nut of this type.

As set forth above, the embodiments of the self-attaching nuts describedabove may be utilized as either a pierce or clinch nut. In either methodof installation, the metal panel is supported in a die press on a diemember or die button. The die button includes an annular clinching lipconfigured to be received in the annular groove generally havingoutwardly tapered surfaces as is known in this art. In a conventionalapplication, the die button is located in the lower die shoe of a diepress and the self-attaching nut is received in an installation headlocated in the upper die shoe having a reciprocating plunger whichdrives the self-attaching nut against the panel. Where theself-attaching nut is utilized as a pierce nut, the end face of thepilot portion pierces or punches an opening in the panel and the annularlip of the die button deforms the panel metal into the annular grooveand against the bottom wall of the groove as is known in this art. Wherethe self-attaching nut is utilized as a clinch nut, an opening ispreformed in the panel configured to receive the pilot portiontherethrough and the annular lip of the die member then deforms thepanel metal into the re-entrant groove and against the bottom wall inthe same manner as described.

As will be understood by those skilled in this art, variousmodifications may be made to the embodiments of the self-attaching nutdescribed above and shown in the attached drawings within the purview ofthe appended claims. For example, the features of the embodimentsdisclosed herein may be utilized alone or in combination as set forthabove. More specifically, the radial notches may be utilized without theradial ribs and vice versa depending upon the requirements of theapplication. However, the preferred embodiments of the self-attachingnut includes radial notches in combination with one of the embodimentsof the radial ribs disclosed herein. In the more preferred embodiments,the radial ribs are generally equally circumferentially spaced andintegral with either the inner or outer side walls of the annular grooveand spaced from the opposed side wall to reduce deformation of thethread cylinder of the bore through the pilot portion. Further, the boremay be unthreaded to receive a self-tapping or thread rolling malefastener. In the more preferred embodiments, the annular groove includesan inner wall inclined toward the outer wall of the annular groove andan outer wall inclined toward the pilot portion and the outer wallincludes radial ribs integral with the outer wall of the annular groove,either integral with the inclined outer side wall or the outer wall ofthe radial notches. The outer wall of the radial notches may beperpendicular to the panel support face, as disclosed in the embodimentsillustrated in the drawings, or the outer wall of the radial notches maybe inclined, preferably toward the pilot portion. Alternatively, theradial ribs may be integral with the inner wall of the annular groove orthe pilot portion or more preferably the self-attaching nut may includealternating circumferentially spaced radial ribs integral with the pilotportion and the outer wall of the annular groove as shown, for example,in FIGS. 16 and 17. Further, in the preferred embodiments, the bottomwall of the annular groove is generally perpendicular to the axis of thebore through the pilot portion or parallel to the panel support face.However, the bottom wall may also be angled inwardly toward the pilotportion. As will be understood by those skilled in this art, however,the bottom wall will generally be inclined toward the pilot portionabout one to three degrees to permit removal of the self-attaching nutfrom the die member of the cold header following formation of theself-attaching nut of this invention. In the preferred embodiments ofthe self-attaching nut of this invention, the radial ribs are integralwith either the inner or outer side walls of the annular groove at orabove a midportion of the side wall. Having described several preferredembodiments of the self-attaching nut of this invention, the inventionis now claimed as follows.

1-56. (canceled)
 57. A self-attaching nut for attachment to a panel,comprising: a body portion having an end face, a central pilot portionprojecting from said end face of said body portion having a boretherethrough, an annular groove in said end face of said body portionsurrounding said pilot portion and an annular panel support facesurrounding said annular groove, said annular groove including an innerside wall adjacent said pilot portion, a bottom wall and an outer sidewall, and a plurality of circumferentially spaced radial ribs integralwith one of said inner and outer side walls having an end portion spacedfrom the other of said inner and outer side walls, and said end portionof said radial ribs inclined inwardly to said bottom wall of saidannular groove forming an undercut for receipt of said paneltherebeneath.
 58. The self-attaching nut as defined in claim 57, whereinsaid outer side wall of said annular groove includes a plurality ofcircumferentially spaced radial notches.
 59. The self-attaching nut asdefined in claim 58, wherein said radial notches each includes an outerwall and opposed generally radial walls.
 60. The self-attaching nut asdefined in claim 59, wherein said radial ribs are integral with saidouter wall of said radial notches.
 61. The self-attaching nut as definedin claim 57, wherein said radial notches extend from said bottom wall ofsaid annular groove to said annular panel support face. 62-67.(canceled)
 68. A self-attaching nut for attachment to a panel,comprising: a body portion including an end face, a central pilotportion projecting from said end face, an annular groove in said endface surrounding said pilot portion having an inner side wall adjacentsaid pilot portion, a bottom wall and an outer side wall, and an annularpanel support face surrounding said annular groove; and a plurality ofcircumferentially spaced generally radial ribs integral with one of saidinner and outer side walls of said annular groove each having a planartop face inclined toward said bottom wall and an end portion spacedabove said bottom wall and spaced from the other of said inner and outerside walls.
 69. The self-attaching nut as defined in claim 68, whereinsaid end portion of said radial ribs is inclined toward said one of saidinner and outer side walls and said bottom wall, forming an undercut.70. The self-attaching nut as defined in claim 69, wherein said undercutend portion of said ribs is generally planar.
 71. The self-attaching nutas defined in claim 68, wherein said outer side wall of said annulargroove includes circumferentially spaced notches.
 72. The self-attachingnut as defined in claim 71, wherein said notches are channel-shapedopening into said annular groove, each notch having an outer wall andopposed side walls.
 73. The self-attaching nut as defined in claim 71,wherein said radial ribs are integral with said outer wall of saidnotches.
 74. The self-attaching nut as defined in claim 68, wherein saidradial ribs are integral with said outer side wall of said annulargroove and said inner side wall is inclined outerwardly toward saidouter side wall, whereby deformation of panel against said planar topface of said radial ribs deforms panel radially inwardly beneath saidinclined inner side wall.
 75. The self-attaching nut as defined in claim57, wherein each of said radial ribs includes a planar top face inclinedtoward said bottom wall.